Apparatus for forming concrete pipes



Dec. 9, 1958 F. E. SEAMAN ETAL 2,853,205

APPARATUS FOR FORMING CONCRETE PIPES Filed Aug. 6. 1955 s Sheets-Sheet 1 F|G.l 20

/3 l3 INVENTORS ATTORNEY Dec. 9, 1958 F. E. SEAMAN ET AL 2,363,205

APPARATUS FOR FORMING CONCRETE PIPES Filed Aug. 6. 1955 3 Sheets-Sheet 2 IV 5 l5" /0 /4 49 ,ea 48 62 n 4 53 54 64 55 59 J J r 52 i 59a J 546R- 5 -5'5a I N VEN TORS 1 .rknxvr/setsznmmv m... Rama- 0 aarrsc/Mzx A BY A \5 ,w /5 Mar/ma ATTORNEY Dec. 9, 1958 F. E. SEAMAN ET AL 2,353,205

APPARATUS FOR FORMING CONCRETE PIPES 5 Sheets-Sheet 3 INVENTORS Filed Aug. 6. 1953 FIG?) pipe.

Unitd ttes 2,563,205 APPARATUS FOR FORMING CONCRETE PIPES Application August 6, 1953, Serial No. 372,742

2 Claims. (Cl. 25-39) This invention. relates to. the manufacture .of concrete pipe, and especiallyto an apparatus for forming a hard, closely-grained smooth and true surface for the socket of the bell of a bell-ended pipe.

Centrifugally spun concrete pipes have structural characteristics which make centrifuging procedure desirable for manufacturing pipes for a variety of applications, but while such pipes have strong walls of well-compacted concrete, the centrifugal moulding of a bell-ended pipe presents problems which too frequently adversely affect the quality of the inner surface of a bell, and also impair the production of a socket recess having a circular inner surface of desired dimensions. The surface of a recess should be smooth in order to avoid injury to a gasket when a joint is closed, and the dimensions of the surface of the recess should be accurate within close limits in order to form a secure joint between connecting pipes, irrespective of the type of joint which is intended and whether or not the design of the joining members is such as to provide for the use of a gasket or packing ma terial for the sealing of a joint.

An inside circular form extending into the plastic mass of concrete contained in a mould for centrifugally forming a pipe, is commonly employed for shaping the recess constituting the socket of a bell, but owing to the impermeable nature of such a form, and its disposition radially outward from the main bore of the hollow mass of concrete, water gathers around the form and is restrained thereby from moving radially inward as the mould rotates. The presence of water and of the fine particles of the concrete against the outer surface of the form tends to leave the surface of the pipe socket softer and less water-resistant than the concrete located in re gions more radially removed toward the outside of the This condition is a contributing cause for undesired irregularities in the surface of the socket and renders the surface susceptible to wear to the detriment of obtaining a uniform sealing surface. Such shortcomings may be aggravated by the presence of large stones about the form and proximate the surface of the socket. While the heavier constituents and the large stones contribute materially to the strength of the bell, their presence adjacent the outside of the form is inimical to the production of a sound surface as they sometimes are the cause for leaving a rough surface or a surface vulnerable to injury or erosion, especially if the surface is constituted of poorly coalesced fine constituents, such as is likely to be the case when Water has been restrained by the form. Because of the possibility of such conditions developing in the moulding of a bell-ended pipe, it has heretofore been diflicult to obtain a smooth and accurately dimensioned surface for the socket of the pipe simply by using an inside moulding form.

It is among the objects of the invention to improve the structural characteristics of the bell of a centrifugally spun concrete pipe, and to provide a hard, closely-grained, and smooth surface of revolution accurately dimensioned to predetermined size and shape.

atent The invention is concerned with a new apparatus for forming the interior surface of the bell of a concrete pipe, A form dimensioned and proportioned to mould an enlargedrecessin the end of a hollow mass of concrete is mounted adjacent one end of a centrifugal mould and concentric therewith and in such a manner that the form extends inwardly from the end of the mould. The mould is charged with a relatively dry concrete mix as the mould rotates. .A vibrator is mounted centrally of the form in a manner to impart vibration waves radially through the form and to thelmould. The vibration and rotation of the mould is continued aftera sufiicient amount of concrete has been placed in the mould and until the concrete has levelled off to the desired wall thickness under the combined action of the centrifugal force and the vibration energy induced. When a uniform inside diameter of the pipe is attained, the vibrator is turned off and the mouldspeed is gradually increased to a value consistent with that required to bring about the production ofa suitable pipe wall. The excess water is removed from the inner surface of the concrete.

The spinning of the mould is discontinued while the concrete is still green but firm enough to maintain its moulded shape. The bell-forming form or ring is then removed and while the concrete is still green, the finishing of the face of the bell proceeds.

quantities of moist cement mortar are strewn or thrown between the working surfaces of the shoes and the concrete of the bell. As this, process continues, the shoes work and spread the mortar in such a manner as to produce a hard, closely-grained, smooth and truly circular surface concentric to the axis of the pipe. Means are provided whereby the operator can gauge the building-up of the face of the socket and determine when the face has been finished to the exact diameter desired. Whenthis. endhas been attained, the manufacture of the pipe is complete, except for curing and its removal from the mould.

Referring to the drawing,

Fig. 1 is a longitudinal section of the moulding apparatus;

Fig. 2 is a transverse section on line 2-2 of Fig. 1;

Fig. 3 is an elevational view of a bell-face forming apparatus attached to the left end of the cylindrical shell of the mould as seen in Fig. 1;

Fig. 4 is a transverse section on line 44 of Fig. 3

showing the bell-face forming apparatus as viewed from the right of Fig. 3.

The main portion of the moulding apparatus illustrated in the drawing includes a longitudinally split cylindrical mould shell 10 and runner rings 11 and 12 which support the mould on rollers 13, arranged as shown in Fig. 2. The mould may be rotated in any conventional manner, as by driving one of the rollers 13. This mould is designed for casting a concrete pipe 14 having a bell is at one endand a spigot 16 at its other end.

The bell end of the mould includes a mould end ring 17 which is supported in place at the end of the mould shell 10 by a plurality of locating bolts 18 engaged in openings in a plurality of bosses 19 which are fast to the shell 10. The runner ring 11 is preferably secured Finishing provides 1 the physical characteristics desired for the interior of the bell and leaves the face of the bell smooth, truly cir- The finishing is accomplished by the use i to the mould end ring 17 and is removable from the shell therewith.

There are four bolts 18, equi-distant from the axis of the mould, and each bolt also supports a keeper or plate 20 which extends beyond the inner edge of the mould end ring 17 and over the exposed end of a device 21 for moulding a recess at theend of a concrete pipe and designated herein as a bell-former. The outer rim of the bellformer engages the inner edge of the mould end ring 17 and is held in place by the screws 22. The bell-former 21 is a circular steel member having. a moulding surface 23 shaped and dimensionedclosely to produce a recess having the configuration desired for the interior of the bell of the pipe. The bell-former 21 and the retaining plates 20 may be removed from the ring 17 and the moulded pipe 14 by drawing them endwise after removal of the bolts 18.

The bell-former 21 is hollow and is provided with a countersunk bore 26 adapted to receive and closely engage the outer rim of a spacing member or spider 27 having a hub 28. A plurality of strips '29, welded to the spider 27, space the bell-former from the plates 20. The hub of the spider has an opening 30 concentric to the axis of the mould for receiving the casing 31 of a vi brator 32. The edge of the opening 30 and the exterior of the casing 31 are tapered and held in tight engagement by a frame 33 supported from the spider 27 and a tightening clamp 34 between the frame and the casing.

The vibrator may be of a conventional form, such as an electric or air motor having an eccentric weight rotatable about the axis of the mould and adapted to transmit vibration waves radially through the spider 27 and the bell-former 21. The vibrator, spider and bell-former are solidly supported with respect to the mould by the bolts 18 connecting between the retaining plates 22, the mould end ring 17, the runner ring 11 and the bosses 19, with the result that the vibrations are transmitted to the concrete in a direction normal to the axis of the mould.

Concrete pipes of various types are formed with bells and spigots for mating at joined ends with the bell and I spigots proportioned and shaped to close the joints with or without allowance for the use of a gasket. Since one of the advantages in having an accurately dimensioned and smooth bell face is to improve on the sealing quality of joints wherein gaskets'of relatively soft materials are employed, such as rubber, the spigot of the pipe illustrated in Fig. l is proportioned and shaped for such purpose, but it is evident that the spigot may be made in other forms. As shown in Fig. 1, the moulding of the spigot is attained by a split ring 38 formed to provide a shoulder 39 for the pipe and a spigot face 40 having an annular recess 41 for receiving a gasket for sealing 'between connected pipes. The segments of the ring 38 are connected to a ring or to retaining plates 42 by the screws 43 and the retaining plates 42 are held in position with respect to the ring 44, the runner ring 12 and the bosses 45 by a plurality of bolts 46 extending through aligned openings in these elements. The bosses 45, like the bosses 19, are fixed to the shell 10 of the mould.

For moulding a concrete pipe the mould is assembled as illustrated in Figs. 1 and 2 with the bell former 21 and the vibrator 31 mounted in place. The requisite amount of concrete for making the pipe is introduced as the mould is rotated. The concrete may consist of an argillaceous calciferous substance, such as Portland cement, crushed stone, sand and only sufficient water to form a relatively dry mix, preferably approaching zero slump. The operation of the vibrator hastens the distribution, compaction and leveling off of the concrete. After the concrete is spread to a uniform diameter which defines the bore of the pipe, the vibrations are discontinued and the speed of the mould gradually increased to a value which will bring about the production of a suitable pipe wall, that is, a wall having a stone matrix on the outside and extending for about 80% of the wall thickness followed by the arms 54, 55 and 59, respectively.

sand and a well-compacted but thin annulus of cement forming the surface of the interior wall of the pipe. After a few minutes the speed is reduced and the excess water is removed from the inner surface of the concrete by pressurized air and the mould is then brought to rest while the concrete is still green but firm enough to main tain its moulded shape.

During centrifugation, the solids constituting the aggregate within the concrete mix tend to migrate toward the cylindrical wall of the mould and to displace the relatively smaller solids and water toward the inner surface of the concrete mass. Because of this the inner surface of a centrifuged hollow body is relatively softer than the concrete disposed more distant from the axis of rotation. Moreover, the inner surface of a bell of a pipe oftentimes is less smooth and circular than is desired for a bell face because of the tendency for water to collect. against an outer impermeable surface located within the radial dimension of a centrifuged mass of fresh concrete, such as the surface 23 of the bell former, and also because of the presence of the larger of the stones located more distantly from the inner surface of the main bore of the pipe and radially more proximate to the diameter of the moulded recess than to the lesser diameter of the main bore. Under these circumstances a bell face is likely to be the cause for leakage at a joint between connected pipes and leakage is aggravated when relatively soft gaskets are used in making the joints; a rough or irregular bell face will abrade a gasket of rubber or like material and thereby cause further impairment of the sealed qualities of a joint.

It is a purpose of the present invention to attain a bell face in the form of a smooth and accurately dimensioned surface of revolution about the axis of a pipe. The exterior surface 23 of the bell-former 21 is machine-finished and has such a configuration as to produce a recess in the plastic concrete closely approximating the size and shape which the interior of the bell should have. After the concrete has been centrifugated and while it is still green, the bolts 18 are disconnected from the mould and the bell former is replaced by the face-forming apparatus illustrated in Figs. 3 and 4.

The face-forming apparatus includes a spider 48 which has arms 49 bolted to a hub 50 and openings 51 at their outer ends for receiving the bolts 18 by which the apparatus is mounted on the mould and centered with respect to the axis of the mould. This apparatus includes a shaft 52 rotatably supported in the hub 50 and preferably driven from a source of power, such as by a motor 53, having connection with one end of the shaft, but the shaft may be held, if desired, as the mould is rotated. It is readily appreciated that relative rotation between the shaft 52 and the moulded concrete may be attained by rotating either the mould or the shaft, or by rotating both the mould and the shaft at different speeds.

The face-forming apparatus includes a pair of arms 54 and 55 which radially extend, respectively, from the hubs 56 and 57, keyed to the shaft 52. These arms, together with an arm 59, support a trowelling device. or shoe 58. The arm 59 is pivotally mounted on the shaft 52. The apparatus illustrated in the drawing has two of these shoes 58 and 58a similarly supported at opposite sides of the shaft 52. The shoe 58a is supported from the arms 54a, 55a and 59a, extending from the hubs of The shoe-supporting members and shoes at either side of the axis of rotation balance one another. For larger sizes of pipes additional shoes may be provided. In Fig. 4, the trailing end or heel of the shoe 58 and the leading end or toe of the shoe 58a face the observer. Since the two shoes and their supporting means are similar, a detailed description of one of the shoes and its supporting means will suifice for an understanding of the complete construction.

As best seen in Fig. 3, a pin 61 is journalled at the ends of the arms 54 and 55 and a pin 62 is journalled at the end of the arm 59. These pins are connected together by a turnbuckle 63 engaging a threaded member 64 and a threaded member 65, respectively journalled on pins 61 and 62. Adjustment of the turnbuckle causes adjustment in the distance between the pins 61 and 62 and hence adjustment of the angle between the pivoted arm 59 and the arms 54 and 55. The spacing of the pins 61 and 62 affects the angle of the shoe 58 with respect to its circular path of travel.

There is journalled on the pin 61 a shoe-supporting lever 66 having a long arm 67 and a short arm 68. The outer end of the short arm 68 is in the form of a yoke 69 which straddles the flange 70 of the shoe. A pivot pin 71 pivotally connects the yoke and the flange at the toe end of the shoe. A plate 73 is secured to the long arm 67 and extends sideways into the diametrical plane of the arm 54. This plate 73 carries a threaded member 74 having an eye for engaging one end of a spring 75, of which the other end is attached to the arm 54. An adjustable nut 76 sustains the threaded member against the tension of the spring. The spring is provided to rock the lever 66 for pressing the shoe outwardly against the inner surface of the recess of the bell of the concrete pipe.

The limit of rotation of the lever 66 counterclockwise, as seen in Fig. 3, is determined by the screw 77 engaged in a tapped hole 78 in the arm 54, and the screw is axially adjustable for limiting the movement of the lever 66, as desired. As shown in Fig. 3, the shoe is being pressed outwardly into contact with the face of the re cess under the influence of the spring 75.

The heel end of the shoe 58 is supported by a pair of links 79, 80, as best seen in Fig. 4. A pivot pin 81 passes through the outer ends of these links and through the heel end of the flange 70. The inner ends of these links are pivotally connected to the pin 62 which is journalled at the end of the arm 59. The links 79 and 80 and the short arm 68 of the lever 66 are of the same length so that when the distance between the pins 61 and 62 is equal to the distance between the pins 71 and 81, the forming surface of the shoe 58 moves parallel to itself as the lever 66 rocks. By turning the turnbuckle 63 to increase the distance between the pins 61 and 62, the heel end of the shoe 58 is adjustable radially outward with respect to the toe end of the shoe and by shortening the distance between the pins 61 and 62, the heel end of the shoe is adjustable radially inward with respect to the toe end. The turnbuckle provides a means for adjusting the angle of the forming surface of the shoe with respect to the circular surface of the bell over which the shoe travels.

It is apparent that only one turnbuckle is necessary for adjusting the angularity between the pivoted arm 59 and the pair of arms 54 and 55, but by providing two turnbuckles (63 and 63a) a locking relationship between these arms is obtainable. However, if the arm 54a is pivotally supported on the shaft 52 independently of the arm 54, the tilt of the shoe 58a may be set at an angle different from the tilt of the shoe 58.

As the shoes pass over the surface of the recess an operator throws small quantities or snatches of cementitious material against the surface of the recess. The shoes are highly polished and they spread and work this material into the grain of the concrete. The finishing mate rial may consist of a mortar mix containing cement, a very fine mineral filler and fine sand to which a small amount of water is added to make the mix just damp enough to become slightly cohesive, yet not Wet enough to be readily balled. The supplying of the mortar is continued until a smooth surface of the desired diameter is completed entirely around the bell. This finishing operation is completed before the final set of the concrete of the pipe occurs. Upon completion of the finishing operation the shoes are collapsed and withdrawn from the pipe. The pipe is then ready for curing. The leading edge of each shoe has a small radius which merges into the cylindrical surface of the shoe. The crosswise contour of the finishing surface of each shoe is shaped to provide the ultimate interior face of the bell. The shoe illustrated in the drawing has a central straight section parallel to the axis of the pipe with a curved portion at one end which finishes the mouth of the bell and a curved portion at its other end which finishes the shoulder of the bell in a gradual change between the diameter of the central straight section and the smaller diameter of the pipe bore. While the bell-former and shoes disclosed are admirably suited for producing a joint-socket adapted for enclosing a gasket within a joint, it is not intended to confine the invention to the embodiment herein disclosed since the invention is susceptible of embodiment in other forms for finishing joint sockets of different types and for finishing the bell faces of pipes which are initially formed as hollow bodies in stationary or rotary moulds within the scope of the claims which follow.

What is claimed is:

1. In apparatus for forming the interior of a bell of a concrete pipe, a pipe mould, means for finishing the face of a circular recess at one end of the main body of a concrete pipe contained in said mould to form a joint socket having a mean diameter greater than the diameter of the bore of said pipe, said finishing means comprising a shoe having an outer finishing surface shaped laterally to conform to the contour desired for the interior surface of said bell, means for moving said shoe over said surface in a plane normal to the axis of said mould, said means including a rotatable shaft, means supporting said shaft at the axis of said mould, an arm fixed to said shaft, a second arm loosely mounted on said shaft and angularly disposed with respect to said fixed arm, means connecting said fixed and loosely mounted arms, a link connecting said fixed arm to the toe of said shoe, a link connecting said loose arm to the heel of said shoe, and resilient means for pivoting said shoe and said links for pressing said shoe against said surface of revolution, said lastnamed means including a member connected to and movable with one of said links and a spring connecting between said member and one of said arms.

2. The apparatus set forth in claim 1 wherein said means connecting said fixed arm and said loosely mounted arm is constructed and arranged to vary the spacing between said arms for effecting changes in the inclination of the shoe with respect to the tangent of said circular recess.

References Cited in the file of this patent UNITED STATES PATENTS 1,750,138 Sorensen Mar. 11, 1930 1,899,115 Schutz Feb. 28, 1933 1,954,904 Walter Apr. 17, 1934 1,984,863 Clark et al. Dec. 18, 1934 2,189,071 Kopp Feb. 6, 1940 2,281,731 Tuerck May 5, 1942 2,399,321 Butler Apr. 30, 1946 2,404,464 Sewell July 23, 1946 2,484,018 Crom Oct. 11, 1949 2,575,353 MacEvoy Nov. 20, 1951 2,602,469 Whiting July 8, 1952 2,703,916 Butler Mar. 15, 1955 FOREIGN PATENTS 269,262 Great Britain Apr. 19, 1927 489,298 Great Britain July 22, 1938 

